Telephone-switchboard circuit



No. 623,437. Patented Apr. l8, I899.

E. H. SMYTHE. V TELEPHONE SWITCHBOABD CIRCUIT.

(Application filed Feb. 23, 1898.)

(No Model.)

41- Invento Urrr. STATES PATENT men.

EDlVIN II. SMYTHE, OF FREEPORT, ILLINOIS, ASSIGNOR TO THE AMERICAN BELLTELEPHONE COMPANY, OF BOSTON, MASSACHUSETTS.

TELEPHONE-SWITCHBOARD CIRCUIT.

SPECIFICATION forming part of Letters Patent No. 623,437, dated April18, 1899.

Application filed February 23, 1898. Serial No. 671,360. (No model.)

T at whom it may concern: tomatic signaling-circuits having one or moreBe it known that I, EDWIN H. SMYTHE,16 substations in circuit can beinterconnected siding at Freeport, in the county of Stephenat the sameswitchboardtable and with the son and State of Illinois, have inventedcersame pairs of linking or switching cords and 5tainImprovementsinTelephone-Switchboard plugs that are used to unitesubstation-cir- Circuits, of which the following is a specificacuits ofthe same kind, so that the discontion. necting or supervisory signalsare readily op- To meet the requirements of modern teleerated with everypossible combination of conphone service, several difierent kinds ofsysnections and without requiring switch cords IO tems of substationapparatus and circuits and plugs of diverse character.

have been devised, the members of all of By means of the invention itbecomes poswhich have to be provided with means for sible to place theterminals of the automatic linking one with the other for throughcomcall or party-line circuits upon the same munication at the centralstation at which switchboard,togetherwith dissiinilarcircuits, 15 theyterminate or to which they converge. instead of locating them at aspecial section It is well known that a substation is supof the board,and they may be connected beplied with means for calling the centralofiice tween themselves orwith lines of other classes when a connectionwith another substation is by the same means as is employed in thecondesired and also with means for ordering a nection or interconnectionof the more ordi- 7o 20 disconnection from the circuit of such othernary circuits.

substation, and the most common form and In carrying out the inventionthe magnetoarrangement of circuit and apparatus is that generatorsubstation circuits are provided in whicha magneto-generator isemployedin at the central station with spring-jacks or sending the callto operate an electromagswitch-sockets and annunciatorsin theusual 2 5netic line-annunciator placed at the central manner and the test-ringsof the sockets or station, the same generator being employed jacks areconnected to ground. The autoto cause an electromagnetic device in thecordmatic signal substation-circuits are branched circuit to indicatethe Wish for a disconnecinto their several substations and haveacalltion. Among other forms of circuit, howbell and condenser in abridge between the 3o ever, which have been devised is one in which mainconductors, which are shunted by the the removal of the telephone at thesubstatelephones when the receiving-telephone is tion and the consequentclosure or alteration off its hook, or, alternatively, the station-bellsof the circuit by the automatic rising of the may be in ground branchesfrom the two hook-switch,permittingthe circulation ot'curmainconductors, as described in the patent 35 rent from a centralized sourceof current of A. S. Hibbard,to which reference has been supply, causesthe line-signal to indicate the made. Means are provided for momentarilycall, and in like manner when the telephone grounding one side of theline direct'when is hung upon the hook-switch the centralized thetelephone is removed and also when it is source of energy operates theclosing-out or replaced upon the hook-switch. At the ceno 40 supervisorysignal. Moreover, various artral station one conductor of the linetermirangements of these types of circuithave been nates at thetest-rings, while the other condevised, some having but one substationon ductorterminates at the plug-tip jack-spring, the circuit and othersa plurality of substawhich rests upon a contact connected to the tionson the same circuit. When the latter line-annunciator battery andground. Asec- 5 5 are employed, they may be fitted with select- 0ndspring in the jack adapted to register or ive signals in the mannerindicated by Let'- to be brought into contact With the front ters PatentNo. 555,725, granted to Angus S. sleeve-contact surface of the plug isconnect- Hibbard March 3, 1896, and are then desiged to ground through abattery. nated selective-signal circuits. In providing a cord-circuit toconnect the 50 The present invention provides means two types ofcircuits indicated it was neceswhereby magneto-generator circuits andausary that it should be so constructed that when adisconnecting-current was sent in from a substation having amagneto-generator it should have no opportunity to pass through theconnections and ring the bells of the substations on the connectedparty-line circuit, or for the clearing-out-battery current from anautomatic signal-circuit substation to pass through them to thesubstation having the magnetogenerator. Hence in a board accommodatingbattery-call and magneto-call circuits and where the connections includethese mixed circuits the cord-circuit connection is made conductivelydiscontinuous, and this is done by the use of a condenser in each cordof the circuit or by the similarintroduction of a repeating-coil. Eachplug is provided with a tip and with front and rear sleevecontactsurfaces. The tip and rear sleeve contact surface of each plug areconductively connected with each other, respectively, through themagnet'coils of the clearing-out or disconnecting signal, and constitutethe registering parts of the talking-circuit with the spring-jacks, andthe front sleeve-contact of each plug is connected by a third strand tothe middle point of the said annunciator-magnet coils. By this divisionof the cord-circuit when a clearing-out signal is given from asubstation supplied with a magneto-generator the current passes from thegenerator to line and through the tip of the plug, the supervisorysignal or clearing-out annunciator, the rearward sleeve-contact of theplug, and the test-ring to ground or other return-conductor, and whenthe clearing-out signal is given from one of the automatic signal-linesubstations the circuit is momentarily closed by the hook-switch at saidstation, over which current flows from the central battery by way of theforward sleeve-contact of the plug, one coil of the clearing-out signal,the tip-contact of the plug, and one main conductor of the circuit toground at the substation, all of which I now proceed to describe andclaim.

Of the accompanying drawings, Figure l is a diagram of twotelephone-circuits, one arranged at its substation withmagneto-generator call appliances and the other there provided withautomatic devices for calling and clearing out, both circuits beingshown as terminating at the central office 0 and associated with acord-circuit adapted to link or switch them together. Fig. 2 is adiagram of a cordcircuit, showing a modification in arrangement.

L represents a telephone-circuit extending from a substation A to thecentral station 0, and 27 is its line conductor, which connects at thelatter station with the line-spring 2 of the jack J, this normallyresting upon contact 3, connected through the call-signal D to ground.The jackis provided with a testring 6, united by wire 5 to ground. Itwillbe understood that the circuitL is provided with a jack at all theswitchboard-sections if a multiple switchboard be employed.

M represents the telephone apparatus at the substation, and comprises amagneto-generator and call-bell a, telephone, and a transmitter-battery.

L is a metallic substation-circuit, which, as indicated, is arranged tosupply communication for a plurality of substations, each of a which isconnected by branches 21 and 22 with the conductors 19 and 20,respectively. The branch 21 terminates at the hook-switch 2e, and thebranch 22 includes the receivingtelephone and secondary 2' of theinductioncoil 1 and terminates at the upper limitingstop an. Thelocalcircuit 19 connects with the branch 22 atthe point it and includes theprimary 2' of the induction-coil, transmitter T, and battery randterminates at the limit-stop g. A bell e and condenser h are bridgedbetween the said branches. A projection f from the hook-switch isadapted to swing against the grounded spring 25, forming a transientearth connection for the main conductor 19 when the telephone is removedand replaced. Conductor 2O terminates at the test-ring 15 of theswitch-socket J and conductor 19 connects with the contact-spring 17 ofthe said socket, which spring normally rests upon contact 18, giving anormal connection by wire 13, call-signal D and battery G to ground. Asecond contact-spring 16 of the jack J has its free end projectingforwardly to a position between the test-ring and the free end of spring17 and at its fixed end is connected by wire 14.- with a battery H andground.

The plugs of the cord-circuit have three contact surfaces-viz. the tipsI) and the front and rear sleeves c and (Z- The cord-circuit shown inFig. 1 is divided into conductivelyseparate but inductivelyunitedterminal loop-sections by the condensers F and F placed between the tipand rear sleeve contacts of the plugs P P respectively, in thecord-strands 7 and 9, and the two loops thus formed between the tip andsleeve contacts I) and d of each plug are made to include in theircircuits, by means of the wires 10 and 11, the clearing-out signals E EThe conducting-strand 8 of the forward sleeve-contacts of the plugsconnects in each case with its loop at a point 12 at the middle of themagnet-winding of the said clearing-out aununciator.

In the cord-circuit shown in Fig. 2 the two loops are conductivelyseparated but inductively united by the repeating induction-coil I,whose windings t' and 2' are connected at their ends to the oppositecords 7 and 9 in each of-the said loops. In this case the loops areclosed in parallel through one winding of the re pea-ting-coil andthrough their clearingout signals, but neither interferes with theoperation of the other.

In the operation of the invention the subscriber at substation A, inmakinga call, actuates the magneto-generator and causes the operation ofthe line-signal D in the usual IIO manner. When the plug P is insertedinto the jack J, its tip l) raises the spring 2 from contact 3 and thecord strand 7 is made continuous with the conductor 27, and when thesubscriber rings otf current from the generator flows by conductor 27,spring 2 of the jack, tip-contact Z) of plug, cord-strands 7 and 10,signal E, cord-strands l1 and 9, rearward sleeve-contact d, test-ring 6,and wire 5 to ground; and when a subscriber at B wishes to signal thecentral station he removes the telephone t from the switch 24, whichrises to make contact with the limitstops 9 and m, while the part f,moving reversely, makes momentary contact with the sprin and completes acircuit by way of the ground, wire 26, spring 25, switch 24, wire 21,conductor 19, spring 17 of jack or socket-switch J cont-act 18, wire 13,line-signal D and battery G to ground, over which current flows, whichcauses the shutter of the signal to fall and indicate the reception of acall. When the plug P is inserted in jack J its tip-contact b registerswith spring 17, the sleeve-contact c with spring 16, and thesleeve-contact cl with test ring or frame 15, and the spring 17 is thusraised from the point 18, thereby cutting off the line-signal andbattery. lVhen the telephone at Bis returned to the hook-switch, itsweight depresses the same and the part f rising makes transient contactwith the spring 25 and closes a circuit for the current of battery Hfrom ground by way of wire 26, spring 25, switch 24, wire 21, conductor19, spring 17 of jack J tipcontact Z) of plug P cord-strands 7 and 10,one coil of signal E cord-strand 8, sleevecontact 0, spring 16, wire14:, and battery H to ground, over which current flows from. the battery11, which causes the operation of the signal E indicating to theoperator that the communication is finished and that the lines may nowbe disconnected.

130th plugs have the same construction, and each is perfectly adapted tooperate with jacks or sockets of either character shown, the onlydifference in the structure of the system being located in theplug-sockets and the only difference in operation consisting in the factthat when inserted in such a socket as J the tip and rear sleevecontacts of the plug only are concerned, while when placed in such asocket as J all three contacts are employed. In the former case thecurrents operating the disconnecting-signal pass through both coilsthereof, but in the latter case through one coil only. Experience has,however, shown that under the conditions of the latter case one coil canbe relied upon for the certain operation of the signal. I

The invention and its mode of operation being thus disclosed, I defineit particularly in the following claims:

1. In a telephoneswitchboard apparatus, a switch-plug and cord-circuitconnection comprising two terminal switch-plugs, each having two maincontact-surfaces adapted to engage spring-jack contacts; twoinductivelycontinuous but conductively-discontinuous mainstrand-conductors extending respectively between the correspondingcontacts 0t the said plugs; and a disconnecting signaldeconnecting-signals bridged between the said two strands, one on eachside of the said condensers or induction-coils; substantially asdescribed.

3. The combination in a telephone system, of a series of main circuitswhose clearing-out current is broughtinto action by temporarilygrounding the line at a substation and a second series of main circuitshaving a magnetogenerator at their substations, and Whose clearing-outcurrent is developed by the operation of said generator; with aswitch-cord connection having terminal plugs adapted for insertion inthe switch-sockets of the said lines respectively, the said cordconnection being divided by interposed induction devices one in eachcord-strand,into two conductivelyseparate, but inductively unitedterminal loop-sections; each extending between the two maincontact-surfaces of its own plug through an independent clearing-outannunciator; and means for bringing the clearingout annunciator ofeither terminal loop-section (when any two main circuits are united bythe said switch-cord connection) into operative relation with thesignal-sending appliances of the main circuit connected therewith,without regard to the series to which the said main circuit belongs;substantially as and for the purposes specified.

4C. 111 a telephone central-station apparatus, the combination of aspring-jack or switchsocket having two main switch-contacts, and anauxiliary switch-contact united to a source of current; and aplug-and-cord switch connection comprising terminal switch-plugs, eachhaving three contact-surfaces adapted to engage the said threesocket-contacts respectively, two main strands extending be tween thecorresponding main contacts of the said two plugs, two inductive devicesone in each stn nd, dividing the same conductively; clearing-outannunciators bridged between the strands, one on each side of the saidinductive devices; and a third strand-conductor in each division of thecord connection eX- tending from the middle point of the Winding of thesaid annunciators respectively, to the third plug contact-surface; forthe purposes specified.

5. The combination in a telephone-switch apparatus, of two independentspring-jacks or switch-sockets representing main circuits of diverseconstruction having their switchcontacts differently arranged, or ofdiverse number, but having their main circuit-contacts similarly placed;with a switch-plug having contact-surfaces similar in number andarrangement, to those of the switch=socket containing the greatestnumber of said contacts, and similar in arrangement to those of theremaining socket; substantially as described.

6. In a switch-plug and cord-circuit connection for atelephone-switchboard, a switchplug having three contact-surfaces, twoof which connect with the terminals of a cleartwo subscribing witnesses,this 16th day of 5 February, 1898.

EDWIN H. SMYTHE.

Witnesses:

E. M. JACKSON,

L. G. RICHARDSON.

